1. Field of the Invention
This invention relates to a control system and method of an ASIC (application-specific integrated circuit) used with an image formation system and in particular to a control technique of a reset signal in an ASIC for an image formation system.
2. Description of the Related Art
In recent years, image formation systems such as printers, copiers and facsimile machines produce high quality images at high speeds. In such image formation systems, increasingly the tasks of processing the image formation system have been removed from a main CPU and assigned to an ASIC (application-specific integrated circuit) that act as a dedicated coprocessor to the main CPU. The ASIC contains several modules depending on the complexity of the processing flow. Further, several registers are assigned to each module. At the termination of a processing sequence in the ASIC, a specific register needs to be cleared for use in the next processing cycle.
Previously, when a register needs to be cleared, a hardware reset method using an external signal or a software reset method for generating a reset signal by accessing a specific address have been used.
In a hardware reset, if the user stops power supply when voltage falls below a given threshold value, a reset signal is generated by hardware and is supplied to the ASIC from the outside; thereby clearing all the registers in the ASIC.
In the software reset, all the registers in the ASIC can be cleared using a program. A specific register can also be cleared selectively by accessing a specific address.
However, if all the registers in the ASIC are initialized by the hardware or software reset method at the stage of the termination of a processing sequence, registers, buffers, etc., that store data that is required in the next processing is also cleared. In such a case, the registers must be initialized with the same data several times wasting time in the process.
On the other hand, the software reset method allows accessing specific registers as described above. Nevertheless, programming, particularly timing, such a software method is difficult. It also leads to lowering of the processing speed.